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At least 73 records · Page 4Linked to original sources
PubMed1995

A portable software tool for computing digitally reconstructed radiographs.

PURPOSE: To develop a portable software tool for fast computation of digitally reconstructed radiographs (DRR) with a friendly user interface and versatile image format and display options. To provide a means for interfacing with commercial and custom three-dimensional (3D) treatment planning systems. To make the tool freely available to the Radiation Oncology community. METHODS AND MATERIALS: A computer program for computing DRRs was enhanced with new features and rewritten to increase computational efficiency. A graphical user interface was added to improve ease of data input and DRR display. Installer, programmer, and user manuals were written, and installation test data sets were developed. The code conforms to the specifications of the Cooperative Working Group (CWG) of the National Cancer Institute (NCI) Contract on Radiotherapy Treatment Planning Tools. RESULTS: The interface allows the user to select DRR input data and image formats primarily by point-and-click mouse operations. Digitally reconstructed radiograph formats are predefined by configuration files that specify 19 calculation parameters. Enhancements include improved contrast resolution for visualizing surgical clips, an extended source model to stimulate the penumbra region in a computed port film, and the ability to easily modify the CT numbers of objects contoured on the planning computed tomography (CT) scans. CONCLUSIONS: The DRR tool can be used with 3D planning systems that lack this functionality, or perhaps improve the quality and functionality of existing DRR software. The tool can be interfaced to 3D planning systems that run on most modern graphics workstations, and can also function as a stand-alone program.

Radiographic Image Enhancement↗
PubMed1988

[Videodensitometric analysis of the characteristics of coronary blood flow using computed digital angiography in patients with ischemic heart disease].

Videodensitometry with following computer analysis of the image obtained by digital subtraction angiography is a method allowing an objective quantitative evaluation of the volume rate of coronary and myocardial blood flow. The moment of contrast appearance in the myocardium as well as the moment of peak concentration, half elimination period and contrast passage period should be taken into consideration. These parametres were significantly increased in patients with obstruction of the left descending artery (LDA) compared to control. At the same time coronary blood flow indexes in patients with advanced stenosis of LDA did not differ significantly from those in patients with normal LDA which could be associated with unaltered coronary and myocardial hemodynamics at rest.

Adult↗
PubMed1996

The measurement of molar furcation defect fill using digital computer technology--report on a new technique.

Recent advances in digital imaging technology have opened up new horizons for dental researchers. This study demonstrates the efficacy of a new technique for measuring regeneration in surgically created molar furcal defects. The investigators evaluated histologic material from a recently completed animal study using five adult baboons. In the animal study, surgically created molar furcation defects were treated using the principles of guided tissue regeneration. From the histologic data of one animal a computer calculated the volume of new bone, connective tissue, epithelium, and cementum as a percentage of the original defect size. The results of this study indicated that digital imaging technology is a useful research tool for determining the volume of defect fill in surgically treated Grade II molar furcation defects in the baboon animal model.

Animals↗
PubMed1992

The classification of asbestos fibres by scanning electron microscopy and computer-digitizing tablet.

Because of the need to completely and accurately size asbestos bulk samples for toxicity studies, a method was developed to classify asbestos fibres using enlarged micrographs originally produced on the scanning electron microscope (SEM). Individual fibre length and width measurements were performed on a computer-assisted, digitizing tablet. This method, though time consuming, permitted the sizing of all fibres (length and width) and particles (area) in selected fields of view at SEM magnifications of x100 and x2500. Final enlargement of the micrographs permitted sizing magnifications of x10,000. Seven distinct asbestos samples were classified including five chrysotile and two crocidolite samples. Statistical analyses showed good interfilter fibre size correlation for all types of asbestos. In addition, it was determined that a representative sizing of all fibres and non-fibrous particles on a filter preparation could be performed using five sets of micrographs taken at a magnification of x2500 and enlarged to x10,000: an inverse square root transformation (-0.5 power) is needed to normalize the distributions of length and width.

Analysis of Variance↗
PubMed1987

Analog and digital computer theory.

Analog signals abound in the natural world. With appropriate transducers these signals can be converted to continuous voltages and can be displayed, transmitted, stored, or copied. They can be processed by analog computers, the simplest of which is an audio amplifier. With analog signals, however, there can be errors because of signals loss, interference, and noise. Binary digital signals permit only two values, either 0 ('off' or 'low') or 1 ('on' or 'high'). These signals are much less susceptible to transmission problems. Binary signals are commonly organized into 8-bit groups which can represent 256 different numbers or meanings. These data can be transmitted in either serial or parallel fashion at high rates of speed. Analog-to-digital converters permit analog signals to be transformed to digital signals. A computer consists of the memory, the processor, and the input/output devices. Memory includes the fastest registers, the very fast core memory, the peripheral storage devices such as diskettes and disks, and the very slow peripheral devices such as magnetic tape. The processor can only load and store numbers in memory, add two numbers, test a number, and provide input and output. The program counter indicates the next computer instruction to be performed. Input/output devices allow communication with the outside world and may assume many forms. A computer by itself can do nothing. A program or series of instructions is required. The most simplistic program language is assembler or machine language. Most programming is done in more sophisticated languages, however.(ABSTRACT TRUNCATED AT 250 WORDS)

Analog-Digital Conversion↗
PubMed1991

Analysis of breath sounds in normal and asthmatic children and adults using computer digitized airway phonopneumography (CDAP).

Analysis of breath sounds using the stethoscope is a major part of physicians evaluation of their patients. However, the use of a stethoscope is often inadequate to give quantitative measurements of the clinical state of the individual. In this study a modification of a previously described computer analysis of breath sounds was used to measure sound intensity levels in both normal and asthmatic children who, in most cases, were unable to perform pulmonary function. The intensity levels were derived using a microcomputer-based program that digitizes audio signals and calculates energy values at 25-ms intervals throughout each signal. There were statistical differences between mean intensity levels for normal breath sounds in children between 2 and 6 years and the mean intensity levels for wheezing sounds in the same age group, as well as wheezing sounds in asthmatic patients over the age of 8 years (P less than 0.002). Also, the mean intensity levels for normal breath sounds could be clearly differentiated from intensity levels for other sounds from the chest, including heart sounds and voice sounds. Thus, computer digitized airway phonopneumography (CDAP) proved to be a reproducible, quantifiable method for demonstrating airway obstruction in those children and patients unable to perform pulmonary function testing.

Adolescent↗
PubMedDate not supplied

Digital computers in nuclear medicine. An overview.

Just a few years ago the role of digital processing and display in nuclear medicine was in question. With the emergence of applications that make the value of digital processing more evident plus the favorable trends in digital equipment price and performance, the controversy has died away. The use of computers to acquire, process, and display radionuclide measurements is now routine in many hospitals and research laboratories.

Computers↗